Space stations, explained: from Salyut to the commercial era

Humans have been living in orbit, on and off, since 1971, and without a single day's break since November 2000. The International Space Station made that streak possible, but it is now in its final years, with a deorbit vehicle under contract, a bill in Congress that would push retirement to 2032, and successors racing to be ready. This guide covers the whole arc: why stations exist, the ones that came first, how the ISS works, and what flies next.

Why put a laboratory in orbit?

Sustained microgravity is the one condition no lab on Earth can fake for more than seconds. Aboard a station, flames burn as spheres, fluids behave without buoyancy, protein crystals grow more perfectly for drug research, and the Cold Atom Lab chills atoms into quantum states. Just as important is the medicine: NASA's Twins Study compared Scott Kelly's 340 days in orbit against his identical twin on the ground, and the station's life support now recycles about 98 percent of the water crews use, a number that has to hold before anyone attempts a multi-year Mars voyage.

The first generation: Salyut, Skylab, and Mir

The Soviet Union flew the first station, Salyut 1, in April 1971, opening the era of living and working in space. America answered with Skylab in May 1973, hosting three crews and proving people could work in orbit for months. The decisive step was Mir, whose first module launched in February 1986: assembled piece by piece over a decade, it became the first long-duration modular outpost and set endurance records that stood for decades. Every station since, including China's, follows Mir's modular blueprint. The timeline traces each of these milestones.

How does the ISS work?

The ISS is a partnership of five agencies (NASA, Roscosmos, ESA, JAXA, and Canada's CSA) representing 15 nations. Assembly began with the Zarya module in November 1998 and took more than 40 flights; the finished station spans 109 meters, masses about 420 tonnes, and circles Earth every 90 minutes at roughly 400 kilometers. It has been continuously occupied since November 2, 2000 and has hosted more than 290 people from 26 countries. Building and maintaining it has taken 281 spacewalks, the most recent on August 6, 2026, when Jessica Meir and Anil Menon spent six and a half hours preparing a power channel for a new roll-out solar array. It is also regularly visible from your backyard as one of the brightest objects in the night sky.

Who flies there, and how?

Crews originally rotated on the Space Shuttle and Russia's Soyuz, which became the only ride after the shuttle retired in 2011. NASA's Commercial Crew Program ended that dependence: SpaceX's Dragon had flown twelve operational rotations by February 2026, with Crew-13 planned for no earlier than September 12, 2026. Boeing's Starliner has yet to carry an operational crew; NASA converted its next flight to an uncrewed cargo run in November 2025, and by July 2026 Boeing did not expect to fly it before the fourth quarter of the year. Supplies arrive on cargo Dragons, Northrop Grumman's Cygnus, Russia's Progress, and Japan's HTV-X, which made its first delivery in October 2025. A seat-barter arrangement keeps crews integrated: cosmonauts fly on Dragon while NASA astronauts fly on Soyuz.

When does the ISS come down?

The United States, Canada, Japan, and ESA have committed to operate the station through 2030, and NASA says Russia is also planning Russian-segment operations through 2030. NASA awarded SpaceX a development contract worth up to 843 million dollars for the US Deorbit Vehicle. NASA will own and operate the completed vehicle and procure its launch separately. The vehicle is meant to dock before the final crew leaves, support gradual orbital lowering, and steer the complex into a remote ocean corridor for a controlled reentry expected in 2031. NASA officials estimated the whole deorbit effort at about 1.5 billion dollars in 2024. None of this is immutable politics. In March 2026 the Senate Commerce Committee approved a NASA authorization bill that would direct operations through 2032, but committee approval did not make it law. NASA also sought industry input on a separate government-owned core-module concept that could first attach to the ISS and later detach; that request was an additional procurement path, not a decision to keep the full station flying into the mid-2030s.

What replaces it?

One successor is already flying: China's Tiangong, assembled in 2021-2022 from three modules and permanently staffed by three-person crews, built after US law excluded China from the ISS partnership (see CNSA). It handled its first in-orbit emergency in late 2025, when a suspected debris strike cracked a window on the docked Shenzhou 20 capsule and China launched a replacement spacecraft six months early to restore a ride home. Shenzhou 23 arrived in May 2026, and the station expects its first foreign visitor, a Pakistani payload specialist, around late 2026. On the commercial side, NASA supports Axiom Space, Starlab, and Blue Origin's Orbital Reef through earlier development agreements. In July 2026 NASA issued a draft request for proposals for the next phase of its original commercial-destination strategy, with a final solicitation then planned for August and awards for spring 2027. The government-owned core-module concept remained an additional path for industry feedback, not a replacement for that procurement. Vast's privately funded Haven-1, a short-stay single module rather than a full ISS replacement, was in integration with a company target of flight readiness in the first quarter of 2027.

Frequently asked questions

How many space stations are in orbit right now?

Two: the International Space Station and China's Tiangong. Both are permanently crewed.

How long have humans lived in space without a break?

Continuously since November 2, 2000, when Expedition 1 boarded the ISS. The streak passed 25 years in November 2025, and Tiangong adds a second uninterrupted human presence.

What happens to the ISS at the end of its life?

A SpaceX-built US Deorbit Vehicle is intended to dock before the final crew leaves and perform the final controlled burn for an expected 2031 reentry over an unpopulated ocean corridor. NASA officials estimated about 1.5 billion dollars for the whole operation in 2024. A Senate bill approved in committee in March 2026 would extend operations through 2032, but it had not become law by August 12.

Will a commercial station be ready before the ISS retires?

That is the open question behind the 2032 extension proposal. Vast's Haven-1 is targeted for the first quarter of 2027 but is a short-stay, single-module outpost rather than an ISS replacement, and the NASA-funded designs from Axiom, Starlab, and Orbital Reef were still in design or early production as of August 2026. NASA's stated goal is to have at least one destination operating before the ISS comes down.

Can private citizens visit a space station?

Yes, at a price. Soyuz carried the first paying visitors from 2001, and Axiom Space has flown private and government-sponsored crews to the ISS on Dragon since 2022, with seats reported around 55 to 70 million dollars. The most recent such flight, Axiom Mission 4, came home in July 2025, and NASA has ordered two more private missions, the first no earlier than January 2027. See space tourism for the full history.